Reduction of copper or trace metal contaminants in plasma electrolytic oxidation coatings

Abstract

A method for creating an oxide layer having a reduced copper concentration over a surface of an object comprising aluminum and copper for use in a semiconductor processing system. The oxide layer produced using a plasma electrolytic oxidation process has a reduced copper peak concentration, which decreases a risk of copper contamination, and includes magnesium oxides that can be converted to magnesium halide upon exposure to an excited halogen-comprising gas or halogen-comprising plasma to increase the erosion/corrosion resistance of the oxide layer.

The invention claimed is: 
     
       1. A method of creating an oxide layer over a surface of an object comprising aluminum, copper and magnesium for use in a semiconductor processing system, the method comprising:
 providing the object, the object comprising a bulk material having:
 a bulk copper concentration between about 0% and about 0.1% by weight; and 
 a bulk magnesium concentration greater than about 1.5% by weight; 
 
 depositing a layer of a second material on the surface of the object, the second material having a second copper concentration less than the bulk copper concentration, 
 oxidizing the surface of the object using a plasma electrolytic oxidation process to form the oxide layer comprising alumina and an oxide of magnesium, the step of oxidizing the surface of the object using a plasma electrolytic oxidation process comprising oxidizing at least a portion of a thickness of the layer of second material; and 
 increasing a magnesium concentration of the layer of second material before formation of the oxide layer. 
 
     
     
       2. The method of  claim 1 , wherein the magnesium concentration of the layer of second material is increased through an ablative transfer of magnesium. 
     
     
       3. The method of  claim 1 , wherein the step of oxidizing the surface of the object using a plasma electrolytic oxidation process comprises oxidizing through and beyond a thickness of the layer of second material into underlying bulk material of the object. 
     
     
       4. The method of  claim 1 , further comprising cleaning the surface of the object prior to depositing the layer of second material. 
     
     
       5. A method for creating an oxide layer over a surface of an object comprising aluminum, copper and magnesium, the method comprising:
 providing the object, the object including a bulk material having a bulk copper concentration by weight and a bulk magnesium concentration by weight; 
 depositing a layer of a second material on the surface of the object, the second material having a second copper concentration smaller than the bulk copper concentration; 
 oxidizing at least an outer thickness of the deposited layer of the second material using a plasma electrolytic oxidation process to form the oxide layer: and 
 increasing the magnesium concentration of the layer of the second material before formation of the oxide layer. 
 
     
     
       6. The method of  claim 5 , wherein the second material includes a magnesium concentration larger than the bulk magnesium concentration. 
     
     
       7. The method of  claim 5 , wherein oxidizing at least an outer thickness of the layer of second material using a plasma electrolytic oxidation process comprises oxidizing at least through an entire thickness of the deposited layer.